When materials that are easily polymerized and solidified by heat, materials that are degraded by heat, or materials having high viscosity are purified, a vertical centrifugal thin film evaporator may be used (for example, Patent Document 1).
As the vertical centrifugal thin film evaporator, for instance, one equipped with a cylindrical body in which an central axis of a circle is set in a vertical direction, a rotor that rotates the interior of the cylindrical body, a wiper that slides on an inner circumferential surface of the cylindrical body, a fixing support that fixes the wiper to the rotor, and a heater that heats the circumferential surface of the cylindrical body is widely used (Patent Document 1). The vertical centrifugal thin film evaporator purifies a material to be purified by introducing a liquid to be processed, which contains the material to be purified, into the interior of the cylindrical body, and by repetitively evaporating and condensing the material to be purified in the interior of the cylindrical body.
However, in the vertical centrifugal thin film evaporator described in Patent Document 1, the liquid to be processed was apt to be retained between the wiper and the fixing support. In the case of the liquid to be processed which was apt to be degraded by heat, if a retention time was prolonged, the liquid to be processed incurred thermal degradation to produce impurities or to give rise to contamination in the cylindrical body, thereby exerting an adverse influence on purification treatment or purity of the material to be purified. Further, in the case of the liquid to be processed which was apt to be polymerized by heat, if a retention time was prolonged, the liquid to be processed was polymerized and solidified, thereby impeding smooth operation of the vertical centrifugal thin film evaporator in some cases.